VIR Vulnerability Intelligence Relay

CVE-2024-42305

medium
Published 2025-05-13 · Modified 2026-05-12
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CVSS v3
5.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v4 NEW
—
not yet in upstream
VIR risk
5.5

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: check dot and dotdot of dx_root before making dir indexed Syzbot reports a issue as follows: ============================================ BUG: unable to handle page fault for address: ffffed11022e24fe PGD 23ffee067 P4D 23ffee067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0 Call Trace: <TASK> make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341 ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451 ext4_rename fs/ext4/namei.c:3936 [inline] ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214 [...] ============================================ The immediate cause of this problem is that there is only one valid dentry for the block to be split during do_split, so split==0 results in out of bounds accesses to the map triggering the issue. do_split unsigned split dx_make_map count = 1 split = count/2 = 0; continued = hash2 == map[split - 1].hash; ---> map[4294967295] The maximum length of a filename is 255 and the minimum block size is 1024, so it is always guaranteed that the number of entries is greater than or equal to 2 when do_split() is called. But syzbot's crafted image has no dot and dotdot in dir, and the dentry distribution in dirblock is as follows: bus dentry1 hole dentry2 free |xx--|xx-------------|...............|xx-------------|...............| 0 12 (8+248)=256 268 256 524 (8+256)=264 788 236 1024 So when renaming dentry1 increases its name_len length by 1, neither hole nor free is sufficient to hold the new dentry, and make_indexed_dir() is called. In make_indexed_dir() it is assumed that the first two entries of the dirblock must be dot and dotdot, so bus and dentry1 are left in dx_root because they are treated as dot and dotdot, and only dentry2 is moved to the new leaf block. That's why count is equal to 1. Therefore add the ext4_check_dx_root() helper function to add more sanity checks to dot and dotdot before starting the conversion to avoid the above issue.

Predictions

Exploit likelihood
55%
Patch ETA
—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

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OS impact
linux Linux kernel Affected 2 releases
VersionStatusFixed in
2.6.19 Affected —
— Affected 4.19.320
suse SUSE Affected 1 release
VersionStatusFixed in
— Affected —
debian Debian Fixed 5 releases
VersionStatusFixed in
trixie Fixed 6.10.3-1
sid Fixed 6.10.3-1
forky Fixed 6.10.3-1
bullseye Fixed 5.10.226-1
bookworm Fixed 6.1.106-1
redhat Red Hat Fixed 1 release
VersionStatusFixed in
9 Fixed —

References

CWEs

CWE-125

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.